Incandescent lamp



April 19, 1949. H. VAN HORN ET AL 2,467,710

INCANDESCENT LAMP Filed June 28, 1946 INVENTORS:

IRVING H. VAN HORN, LEROY G LEIGHTON,

' B MWI LA oabw THEIR ATTORNEY Patented Apr. 19. 1949 INCANDESCENT W Irving H. Van Horn, East Cleveland, and Leroy G. Leighton, Cleveland, Ohio, assignors to General Electric Company, a corporation of New York Application June 28, 1946, Serial No. 679,951

2 Claims.- (Cl. 176-10) 1 Our'invention relates to incandescent lamps, and. more particularly to the prevention of bulb blackening due to vaporization of the filament.

There is at present commercially available an incandescent lamp having an elongated tubular bulb containing an elongated linear filament ex-" tending adjacent the bulb wall. Due to the extended length of the filament the particles va- DOrized therefrom during operation of the lamp 2 respective lead sections. The said sprin members each consists of a bundle of fine tungsten wires, for example about twenty-five strands of 6 milwire. The said spring members ll maintain a tension on the filament 9, The filament mount structure is additionally supported from in its normal horizontal position cover the entire interior surface of the bulb with a very heavy black deposit which seriously diminishes the light output relatively early in the life of a lamp and renders the lamp useless before the filament burns out. This is obviously a serious drawback particularly since such lamps are inherently costly. It is an object of the present invention to obviate that blackening.

According to the present invention we have found that the introduction of a metal screen a short distance above the filament and coextensive therewith prevents such blackening to a' very marked degree. While. metal screens have been used heretofore to control bulb blackening, in none of them has the difference been so pronounced. Moreover, in the type of lamp referred to the screen does not intercept or reduce the useful light from the filament since it is located above the filament and the useful light is that projected downwardly. Further features and advantages of our invention will appear from the following detailed description of a species thereof and from the drawing.

In the drawing, Fig. 1 is an elevation of an incandescent lamp comprising our invention, and Fig. 2-is a section taken along the line 2-2 in Fig. 1.

: Referring to the drawing, the lamp comprises an elongated tubular glass bulb I containing a gas filling, preferably argon mixed with a minor proportion of nitrogen, at a pressure of about 600 mm. A pair of lead-in conductors 2, 3 project into the lamp through a conventional stem 4 at one end thereof. The long conductor 2 comprises an angular section 5 and a long straight section 0 extending longitudinally of the bulb to a point adjacent its remote end. The short conductor 3 comprises an angular section 1 and a short straight section 8 welded thereto. The filament 9 consists of a straight length of tungsten wire secured at one end to the lead wire section 8 and at its other end to an auxiliary section 10 of the lead wire. The said section III is supported from the long lead section 6 by three spring members II which are welded at their ends to the the bulb by means of an angular length of wire I! having one end welded to the lead wire section 6 and having its other end extending into the interior of a hollow glass nipple l3 which is fused to the tip of the bulb.

Lamps of the type thus far described may be operated on a 23. volt source with a current consumption of 21 amperes, for example. However, the bulb l begins to blacken relatively rapidly and may be rendered useless after a period of a few hundred hours.

According to the present invention blackening of the bulb is virtually eliminated by the provision of an elongated screen ll located adjacent to and coextensive with the filament so as to be above the filament in the normal operating po-.

sition of the lamp. The said screen II is thus located in the path of convection currents rising from the filament 9 so that particles vaporized from the'filament are deposited on the screen. It will also be noted that the screen is located close to the filament so that it is rather highly heated during operation of the lamp. The screen itself retains a clean appearance even after many hundred hours of operation. This may be on account of recrystallization of the tungsten particles. Moreover, as shown in the drawing, the filament l is offset from the longitudinal axis of the bulb so as to be adjacent to the bulb wall, and the screen I4 is located between the said bulb axis and the filament.

The screen Il may be made of nickel wire of 0.006" diameter and 20 x 20 mesh. Particularly good results have been obtained with a screen about 6% inches'long and 1% inches wide curved transversely in an arc of about 1% inches radius, the screen being mounted about inch above the filament. It is preferably supported by a wire frame I! of shallow U-shape located substantially in the plane defined by the filament 8 and conductor 6. The ends of the frame ii are preferably welded to the conductor G and the screen is preferably welded along its longitudinal center line to the base portion of the frame. If desired. the portion of the conductor 6 between the let's of the frame II may be eliminated in which case the said frame may be an integral part of the said conductor 8.

3 What we claim as new and desire to secure by Letters Patent of the United States is:

1. A high wattage incandescent electric lamp comprising an elongated tubular gas-filled bulb,

an elongated linear filament extending longitudinally within said bulb and offset from the longitudinal axis of the bulb to be adjacent the bulb wall, lead-in conductors supporting said filament including a conductor parallel to and spaced from said filament, an elongated metallic screen located adjacent to and coextensive with said filament and between said filament and said parallel condoctor as well as between said filament and the bulb axis so as to be above the filament in the normal operatin position of the lamp whereby to collect particles vaporized from the filament, and support wire means secured to and supporting said screen directly from said parallel conductor.

2. A high wattage incandescent electric lamp comprising an elongated tubular gas-filled bulb, a pair of lead-in conductors projecting into the bulb from one end thereof includin' a short conductor and a long conductor extending longitudinally oi the bulb to its remote end, an elongated linear filament extending longitudinally of the bulb narallel to the said long conductor and electrically connected between said short conductor the remote end of said long conductor,

said filament being offset from the longitudinal axis of the bulb to be adjacent the bulb well, an elongated metallic screen located adjacent to and coextensive with said filament and between said filament and said long conductor as well as between said filament and the bulb axis so as to be above the filament in the normal operating position of the lampwhereby to collect particles vaporized from said filament, and a wire support frame of shallow U-shape located in the plane defined by said filament and said long conductor and having its ends secured to said long conductor, the said screen being secured along its 1011- gitudinal center line to the base nortlon of said support frame.

IRVING H. VAN HORN.

LEROY G. LEIGHTON.

REFERENCES CITED The following references are of record in tho file of this patent:

UNITED STATES PATEITEZ Number Name Date 985,422 Knight Feb. 28, 2,183,952 Anderson Dec. 19, 3.939 2,379,958 Anderson June 26, 1945 2,434,779 Willis -l Jan. 2%, 

